I picked up one of the MTB magazines in a supermarket the other day and while not buying it, I read a review on a tyre which wasn’t overly favourable. At the end of the review they stated that ‘reports on these tyres in 650b and 29″ guise are more positive due to the extra grip offered by the larger contact patch’.

I was fairly gobsmacked at the utter twaddle I was reading, I’m no maths expert, but the size of the contact patch on a 650b can’t be large enough over a 26″ to offer any noticeable difference?

The size of the contact patch has more to do with the pressure in the tyre (and your weight) than the diameter of the wheel. If the contact patch is larger with a 650b or 29er then it’s most likely to be either due to the bike being heavier or the tyre pressures being lower.

The size of the contact patch has more to do with the pressure in the tyre (and your weight) than the diameter of the wheel. If the contact patch is larger with a 650b or 29er then it’s most likely to be either due to the bike being heavier or the tyre pressures being lower.

which between 26 and 650b is barely different because they are so close in size.

I wonder what next seasons must have will be and what stadard will be ditched?

Maybe super-oversized taper headsets, 22mm through axles, and 137mm of front end travel, think of the extra stiffness, that 16% less deflection* riding through a rock garden composed of 9.8″ baby heads.

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*compared to a rigid ritchey logic unicrown fork with a qr the rider forgot to do up.

Is it Made Up Bullshit, or is it just them taking a perceived difference and attaching an unconvincing reason? (ie, is the difference made up, or is it just the explanation for the difference that’s made up)

I picked up one of the MTB magazines in a supermarket the other day and while not buying it, I read a review on a tyre which wasn’t overly favourable. At the end of the review they stated that ‘reports on these tyres in 650b and 29″ guise are more positive due to the extra grip offered by the larger contact patch’.

I was fairly gobsmacked at the utter twaddle I was reading, I’m no maths expert, but the size of the contact patch on a 650b can’t be large enough over a 26″ to offer any noticeable difference?

Not twaddle at all , common sense tells you that bigger wheels have a bigger contact patch so more grip , try a 26″ wheeled bike and then a 29er , there is a very noticeable difference .

Of all the tosh that get bandied about in the endless wheelsize debates the stuff on contact patch must rank as the most pointless. In most practical situations there is a trade off between grip and drag and you can find the sweet spot for any conditions by changing tyres and tyre pressures regardless of what size wheels you have.

Of all the tosh that get bandied about in the endless wheelsize debates the stuff on contact patch must rank as the most pointless. In most practical situations there is a trade off between grip and drag and you can find the sweet spot for any conditions by changing tyres and tyre pressures regardless of what size wheels you have.

What you say is true but on a ride where you will ride through varying terrain , ground conditions and gradients you would be stopping to change tyres or tyre pressure every 5 mins if you wanted the ideal tyre and pressure which obviously isn’t practical . It’s always going to be a compromise , many feel that bigger wheels and tyres are better all rounders than 26″ .

Sorry , I like to ride my bike when I go out for a ride not stop every 5 minutes to adjust my tyre pressure . When I get home from that ride I like to clean the bike and put it away until the next time . I certainly don’t want to be thinking where is my next ride going to be and what tyres should I put on for it ?

Think your physics are being a bit too basic here. If you were dealing with perfect, circular wheels that didn’t deform in contact with the ground and had identical curved profiles, then yeah. But realistically a fatbike tyre will have a much squarer profile, and a wider contact patch, even if pressure/deformation etc are all equal.